|Publication number||US7742887 B2|
|Application number||US 10/750,342|
|Publication date||Jun 22, 2010|
|Filing date||Dec 31, 2003|
|Priority date||Nov 24, 2003|
|Also published as||CN1886668A, CN1886668B, US20050114056, WO2005052611A1|
|Publication number||10750342, 750342, US 7742887 B2, US 7742887B2, US-B2-7742887, US7742887 B2, US7742887B2|
|Inventors||Jagrut Viliskumar Patel, Martin Vyungchon Choe, Ziad Mansour|
|Original Assignee||Qualcomm Incorporated|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (25), Non-Patent Citations (4), Referenced by (10), Classifications (18), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a Continuation-in-Part of U.S. application Ser. No. 10/722,350, entitled CALIBRATING AN INTEGRATED CIRCUIT TO AN ELECTRONIC DEVICE, filed Nov. 25, 2003, now abandoned which claims priority to U.S. Provisional Application Ser. No. 60/525,103, entitled CALIBRATING AN INTEGRATED CIRCUIT TO AN ELECTRONIC DEVICE, filed Nov. 24, 2003.
The present disclosure relates to systems and techniques for identifying process and temperature of chips.
The demand for wireless services has led to the development of an ever increasing number of chips, all of which must adhere to strict industry performance standards. Manufacturing of silicon chips is guided in part by standards and tolerances for nominal process speed. Within the guidelines of such standards, chips are designed to run at their rated clock speed for their entire expected lifetime, even in worst-case temperature and voltage conditions. Thus, part of the manufacturing process includes testing manufactured chips to identify their rated clock speed and ensure they are rated properly.
Chips for use in communications devices must generally be rated to operate at a specified nominal speed, within a certain allowed tolerance. However, a set of chips generated from a single wafer commonly will fall into a range of different process speed ratings.
In an attempt to use those portions of the wafer that produce different speed ratings, some manufacturers engage in a method of speed binning, in which the various chips produced from a single wafer are tested and batched according to their graded process speed. Batching chips according to their speed may be time consuming and costly.
Some manufacturers may even discard slow chips and fast chips that are outside of the nominal tolerance range. For example, SDRAM chips require an external clock from the host controller with control and data signals. Because the host clock is sensitive to process speed, temperature and voltage variations, it is possible that a given set of parameters used to generate timing in a controller may not hold true across all process speed, temperature and voltage variations. In such cases speed binning is commonly used. This involves sorting chips according to different speed settings, and even providing software customized for different speeds. Of course, such customized operations can be very costly.
There have been attempts to compensate for effects of a chip's operating temperature on its clock speed, however such methods have proven cumbersome. For example, additional components for measuring chip temperature and providing leads to communicate such temperature to compensation circuitry have been employed in the past. However, the additional components and leads consume valuable space on the silicon chip, and require additional costly manufacturing steps and parts.
Accordingly, there is a need for a methodology wherein all chips from a single wafer are enabled to operate at an industry specification nominal speed, regardless of temperature variations that occur during the wafer fabrication, and regardless of temperature variations that may occur during use. The specific methodology should provide an ability to determine operating temperature and process speed while a chip is in use, without implementing additional chip components or new manufacturing steps.
In one aspect of the invention, a method for determining an operating parameter of a chip having first and second ring oscillators includes measuring a frequency of the first ring oscillator, measuring a frequency of the second ring oscillator, and calculating an operating parameter of the chip as a function of the first and second ring oscillator frequencies.
In another aspect of the invention, computer-readable media embodying a program of instructions is executable by a computer to perform a method of determining an operating parameter of a chip having first and second ring oscillators. The method includes measuring a frequency of the first ring oscillator, measuring a frequency of the second ring oscillator, and calculating an operating parameter of the chip as a function of the first and second ring oscillator frequencies.
In a further aspect of the invention, a system includes a chip and a processor configured to measure the frequencies of first and second ring oscillators on the chip. The processor is further configured to calculate an operating parameter of the chip as a function of the first and second ring oscillator frequencies.
In yet another aspect of the invention, an apparatus for measuring an operating parameter of a chip, the apparatus including means for measuring a frequency of a first ring oscillator, means for measuring a frequency of the second ring oscillator, and means for calculating an operating parameter of the chip as a function of the first and second ring oscillator frequencies.
It is understood that other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
Aspects of the present invention are illustrated by way of example, and not by way of limitation, in the accompanying drawings wherein:
The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention can be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the present invention.
Once the two ring oscillator frequencies have been determined, various methods disclosed herein may be implemented to calculate the operating temperature and process speed of the chip. As with determination of ring oscillator frequencies, the methods described below may be performed by a processor that is also embedded on the chip, or may be performed by a separate processor embedded on a second chip that is operably coupled to the chip whose temperature and process speed are being measured. The methods are based upon measurable relationships between a chip's ring oscillator frequency and its process speed and temperature. Specifically, because the frequency of each of a chip's ring oscillators is a function of the process speed, voltage, and temperature of a chip during operation, different sets of equations according to the particular mathematical relationships can be implemented to calculate either process speed or temperature according to known characterization data of the ring oscillators and the chip. For example, the frequency of the first ring oscillator, f1, and the frequency of the second ring oscillator, f2, are each functions of the change in process speed ΔP, the voltage V, and the temperature T of the chip as follows:
Therefore, the product of the first and second ring oscillators is also a product of those functions:
f 2 ·f 1=ƒ(ΔP2·V·T)(ΔP1·V·T)
It follows that the product of the first and second ring oscillators is a function of process speed, voltage, temperature and a constant K, denoting device delay:
f 2 ·f 1=ƒ(K·ΔP1·ΔP2·V 2 ·T 2)
Because voltage V is constant, and ΔP1·ΔP2>>T2, it follows that the product of the first and second ring oscillators is proportional to the temperature squared, without dependency on process speed:
f 2 ·f 1∝ƒ(T 2)
Similarly, the quotient between f1 and f2 is proportional to the process speed. Thus, an algorithm based upon a series of equations based on the known relationships described above may be implemented to calculate process speed from ring oscillator frequency for a given temperature and voltage.
According to the known relationship of ring oscillator frequency to temperature, which is independent of process speed, exemplary techniques disclosed herein may be used to determine operating temperature of a chip as a function of ring oscillator frequency. In one embodiment, the techniques may implement a series of equations according to a linear model that may be developed through the empirical testing of a large number of chips from various “splits” that are representative of the range of process speeds achieved from an entire production lot. As used herein, the term “split” denotes a set of chips that may be either slower than nominal, faster than nominal, or nominal. A production wafer may include various splits. Because the chips produced from any given wafer will include a range of slow, fast and nominal chips, i.e. a range of different splits, the testing and collection of characterization data across the entire split range can be used to develop a linear model representative of all chips that may be produced from the production lot. Those skilled in the art will recognize various methods of collecting characterization data for this range of chips. For example, chips for gathering empirical data for a particular split may be identified either through a precise manufacturing method in which a wafer is carefully controlled during production to produce only a single type of chip (such as only slow, only nominal or only fast), or by speed binning the resultant chips from manufactured wafers that produce numerous splits.
T 1 =C 1 −C 2·(ƒ−C 3)
T 2 =C 1 −C 2·(ƒ−C 4)
where ƒ represents the product of the two ring oscillator frequencies, and T1 and T2 represent the minimum and maximum temperatures, respectively, that would be expected for the given ƒ within the range of splits. xyz
For any particular chip, the above equations may be implemented to determine temperature T, for a given ƒ, which is simply calculated as the product of two ring oscillator frequencies.
Once the estimated temperature value is known, the process speed of the chip can be calculated. The calculated process speed can then be compensated for based on the estimated temperature.
wherein N represents a normalization factor that is determined by triangulation based on the characterization data. Those skilled in the art will recognize that the characterization data, which may be modeled with a linear equation whose slope defines a change over temperature, may be normalized so that the data is constant over temperature. Using triangulation, a normalization factor N can be calculated such that it causes the slope of the modeled data to be approximately zero, meaning that the normalized data is constant over temperature.
with a reduced expected error of margin of
The above techniques employ a linear model based on characterization data, however it will be recognized by those skilled in the art that other mathematical models may be employed as well. For example, a second order approximation of temperature may be calculated according to the characterization data. In the event that characterization data can be represented by a second order approximation, the temperature estimation would be more accurate than temperature estimation through a series of linear equations as described above.
ƒ2 =−C 1 T+C 2 +K ΔP
ƒ1 =−C 3 T+C 4 +K ΔP
Then, following a simple algebraic procedure for combining the two equations to remove dependency on temperature T, a scaled frequency number derived from characterization data is generated for both process (Pvalue) and temperature (Tvalue):
P value=ƒ2 −C comb·ƒ1
where the value of Ccomb is obtained through the algebraic combination of the two linear equations. With these equations for scaled frequency numbers for process and temperature, graphs of characterization data for a split are made, to represent the entire range of process and temperature scaled frequency numbers. Such graphs would plot Pvalue, versus temperature and Tvalue versus temperature. Then, for a particular measured value of Pvalue or Tvalue for a given chip during use, which as shown above is based solely on the measured ring oscillator frequencies ƒ1, ƒ2 and a known constant Ccomb, the process speed of the chip can be identified from the Pvalue graph of split data and the temperature of the chip can be identified from the Tvalue graph of split data. Of course, it is to be understood that actual graphs and plots are not necessary for implementing the methods disclosed herein. Rather, such graphs and plots of data are used for purposes of clarity in explaining the disclosed methods. Those skilled in the art will recognize that characterization data may be arranged in any format, and need only be referenced to determine particular values of a chip, but need not be referenced in a particular format. For example, characterization data may be used to determine the constants in the equations disclosed herein, which may then be implemented into particular algorithms used to calculate process speed and temperature for a particular chip based upon its operating ring oscillator frequencies.
From the equations above, a second order equation for T can be developed to calculate a more accurate temperature value. Specifically, by multiplying the two frequency equations, the flowing second order equation results:
ƒ1·ƒ2 =C 1 T 2 −C 2 T+C′
where, at C′=C3+ƒ1·ƒ2 ,C 1 T 2 −C 2 T+C=0
The various methods described above for determining process speed and temperature of a chip using its ring oscillator frequencies can be used for a number of applications. The calculations may be achieved by algorithms implemented by software that receives input from the chip or by hardware logic added to the chip or operable in communication with the chip. In either case, the chip may have outputs from two of its ring oscillators enabled so as to provide input for any of the process speed and temperature calculating means described above, or any variation thereof.
The methods or algorithms described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a chip. In the alternative, the processor and the storage medium may reside as discrete components in a chip.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
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|International Classification||G01R31/28, G01R23/00, G11C29/00, G01R31/317|
|Cooperative Classification||G01R31/31718, G11C29/50012, G01R31/31707, G11C2029/5002, G01R31/2882, G11C29/00, G01R31/31725|
|European Classification||G11C29/50C, G01R31/317T, G01R31/317L, G01R31/28G3, G11C29/00, G01R31/317H|
|Jun 30, 2004||AS||Assignment|
Owner name: QUALCOMM INCORPORATED, CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:PATEL, JAGRUT VILISKUMAR;CHOE, MARTIN VYUNGCHON;MANSOUR,ZIAD;REEL/FRAME:014802/0065;SIGNING DATES FROM 20040619 TO 20040628
Owner name: QUALCOMM INCORPORATED,CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:PATEL, JAGRUT VILISKUMAR;CHOE, MARTIN VYUNGCHON;MANSOUR,ZIAD;SIGNING DATES FROM 20040619 TO 20040628;REEL/FRAME:014802/0065
|Nov 26, 2013||FPAY||Fee payment|
Year of fee payment: 4